I'm considering an aftermarket programmable ignition module. I'm wanting a timing increase above 3.5k (where stock timing no longer increases). More importantly, I want to add a vacuum advance to improve performance, throttle response and MPG below WOT. This will require adding a MAP sensor.
I was thinking of running a hose from both carb vacuum ports to a manifold, then running from the manifold to:
The petcock
The air bypass system (yes I left it in after the ear shave)
and the MAP sensor.
Will this sort of cross-connection cause some issues with the carbs?
The rational is this would give a more steady signal to the MAP sensor, since it's reading both carbs. I would also expect the petcock to open sooner on start up, maybe giving a quicker start to fuel flow. In any case, I plan to only use the MAP sensor from 3K-8.5K, to avoid the pulsing vacuum at lower RPMs. I would simply program in stock tuning from idle to 3K at all MAP sensor readings.
It sounds like there's little to gain below 3.5k without risking knock. The same linked thread indicates that there's some gain above 5k though. It looks like dariv is now banned, so I never found out the results of his re-tune. But his last post showed 37 at 5.5k instead of the stock 25! He seemed to be active for another 2-3 years after that, so I'm guessing he didn't blow his engine!
I was thinking of running a hose from both carb vacuum ports to a manifold, then running from the manifold to:
The petcock
The air bypass system (yes I left it in after the ear shave)
and the MAP sensor.
Will this sort of cross-connection cause some issues with the carbs?
The rational is this would give a more steady signal to the MAP sensor, since it's reading both carbs. I would also expect the petcock to open sooner on start up, maybe giving a quicker start to fuel flow. In any case, I plan to only use the MAP sensor from 3K-8.5K, to avoid the pulsing vacuum at lower RPMs. I would simply program in stock tuning from idle to 3K at all MAP sensor readings.
It sounds like there's little to gain below 3.5k without risking knock. The same linked thread indicates that there's some gain above 5k though. It looks like dariv is now banned, so I never found out the results of his re-tune. But his last post showed 37 at 5.5k instead of the stock 25! He seemed to be active for another 2-3 years after that, so I'm guessing he didn't blow his engine!